Oaky, now I'll try to get to travel agent commissions and FF program changes.

As to changes in travel agent commissioning, what has typically happened is that one of the airlines has publicly announced a change to occur at some time in the future. They then have the ability to sit and wait to see whether anyone follows their lead. If no one follows their lead, they have the luxury of cancelling the proposed change, which has not yet taken effect, so that they do not lose any market share or actual sales to the other airlines.
As mentioned before, this constitutes "price signalling." Many years ago, the Department of Justice was more active in prosecuting price signalling cases (either as implicit price-fixing, or as attempted monopolization), but it has not been as active in this area in recent years.

As to changes in FF programs, much the same thing is occurring. However, there is a significant difference. First, the airlines have an "embedded base" of customers who already have huge investments (of earned FF miles) in their accounts. Therefore, those persons are, to some extent, economic hostages, i.e., they can only change allegiances by losing some or all of the value of the FF miles they have already earned.
As to the propriety of changing FF programs, that is really just a contract issue. What did the airline promise in its earlier agreements with the travelers, and did it reserve to itself the discretion to change the program at any time in the future. There was a successful class action against American when it first tried to apply its 3-year expiration policy to all old miles (which had been earned under then program rules saying they would not expire). American lost, having argued that state contract or fraud claims were preempted by the federal laws regulating airlines and fares. Thus, some ofus have those AA miles still in our accounts that have no expiration date.

And that, I think, answers all of the questions to date. Any more, let me know.